Hoffman Amplifiers Tube Amplifier Forum

Other Stuff => Solid State => Topic started by: Twanger on December 19, 2009, 03:11:18 pm

Title: Relay switching noise
Post by: Twanger on December 19, 2009, 03:11:18 pm

Hi all,

In my last project im using a relay to bypass a preamp, im getting a big pop when i engage the relay, is there a fix for that ?

Thanks

John

Title: Re: Relay switching noise
Post by: jcm-jmp on December 19, 2009, 03:40:31 pm

tie a diode across the coil of the relay. and if it still pops use a large 2200uf low voltage cap on the positive side of coil to ground.

Title: Re: Relay switching noise
Post by: tubesornothing on December 19, 2009, 03:46:05 pm

Is the switch in series with the preamp?  This often causes pop, adding another switch shunting to ground cures the pop.

Title: Re: Relay switching noise
Post by: JayB on December 19, 2009, 05:38:50 pm

That or make sure grids are not flying free before and after the relay. They need a ground reference or the voltage builds up after the cap.

Title: Re: Relay switching noise
Post by: Twanger on December 19, 2009, 07:11:17 pm

thank you all for your help, I will try the tricks you proposed and see if it cures the problem.

John